I'm going to finish my basement and I have a question about proper framing. On one wall I'm gluing on rigid foam insulation onto the cement wall and I want to build the 2x4 wall right on top of the insulation. The problem is there are pipes overhead so the walls top plate can not be nailed into the floor framing above. I want to build a 2 walled soffit around the plumbing and attach it to this wall. But, how do I hold up that 2x4 wall? Can it be framed so the soffit supports the wall or do I bolt the 2x4 wall into the cement wall? Any suggestions appreciated.

Without physically seeing the space in question possibly you may want to build your soffit first by attaching a ledger to your masonry wall to have an attachment point for the horizontal portion of your soffit then build your wall and attach your top plate to the soffit framing. Hope this makes sense.

That dose make sense. Thanks.